The Internet of Things (IoT) is a new area of infocommunication technologies. These are not only home appliances with an IP address and Internet control, but also a variety of industrial technologies. Industrial process control, telemedicine, entertainment require new technologies. These technologies need to be developed at all layers of the OSI model, but the need for security mechanisms should be emphasized.
At the physical level, wireless technologies that are rapidly developing (Wi-Fi, Bluetooth) have significant limitations in communication range. The few tens of meters that these standards allow are categorically not enough. Alternative wireless technologies LPWAN (Low-power Wide-area Network) and NB-IoT (Narrow-band Internet of Things) are rapidly developing and are used in many areas, for example, when collecting readings from energy consumption sensors. Their range is an order of magnitude higher than that of Wi-Fi and Bluetooth technologies. But they have one big drawback - there is no generally accepted standard, these technologies are regulated by individual private companies. Nevertheless, several unresolved issues remain, so there are currently attempts to develop new technologies that would lay the foundation of the Internet of Things.
However, there are wireless technologies that are quite old and very well studied. Due to the technological revolution, they are in rather low demand since interest in them has passed. We can try to give such technologies a second life in the field of the Internet of Things. First, this comment concerns the recently rapidly developing technology DECT (digital enhanced cordless telecommunication). This standard operates in the 1.9 GHz band. The peak of interest in the DECT standard was noted before the massive spread of cellular communications. At one time, DECT telephones allowed partial mobility when using the telephone.
After the emergence of the GSM standard, interest in DECT dropped. An attempt to use DECT as a physical layer for TCP/IP was not successful due to low transmission rates. The emergence of demand for IoT technologies gives DECT technology a chance for a rebirth. The basis of this statement is that DECT can increase the communication range between devices up to several hundred meters and achieve a data transfer rate of several hundred kilobits per second. This speed is sufficient for transmitting control and monitoring information in real time.
Let us note the significant advantage of DECT in comparison with the existing standards for the physical layer of the Internet of Things. The frequency band in which DECT operates lacks many different devices, compared to the 2.4 GHz band and the ISM (Industry, Science, Medicine) bands. In 2020, the European Union adopted the DECT-2020-NR standards package, which was developed to support IoT applications . Before that, in 2017, the DECT ULE (Ultra Low Energy) standard was adopted, which describes the principles of working with various types of devices such as sensors.
Let us list once again the advantages that are achieved when using DECT technology.
- Increased action at a distance. Modern standards provide for stable communication with a separation of devices at a distance of up to 600 meters
- Availability of ULE technology to extend the service life without recharging each device and the entire network of devices.
- Technologies for protecting data transmission, implemented at the physical layer of the OSI model (radio path level)
- The ability to build a network infrastructure for mobile terminals without losing communication during transitions between base stations (handover)
- A large number of ready-made standards approved by ETSI in 2020
The IP over DECT data network should become a key component of a full-fledged family of IoT technologies. The ability to transfer data over the IP protocol, assigning an IP address to a subscriber terminal are the basic elements of the proposed concept. Fortunately, this problem has been solved, VoIP support has long been included in the DECT standard.
Currently, there are implementations of DECT phones in which the subscriber device is an Android device that supports the TCP / IP protocol stack. Consequently, this device is assigned an IP address and can operate using all the capabilities of the IP protocol, including packet data transmission. There are currently many IoT MQTT (Message Queue Telemetry Transport)  implementations available for the Android platform, making the testing process easier. The DECT base station can be implemented based on a standard Linux server with a specialized PCI card.
It should be noted that in the cases described above, there is no need for high data transfer rates, and the speed at which voice transmission is organized is quite enough for IoT tasks.
The presence on the market of Android devices with DECT support makes it quite easy to assemble an experimental bench for various tests and measurements. In connection with the above, the team of authors expects the appearance of DECT subscriber devices based on minicomputers with a DECT module running Linux and Android operating systems. The emergence of such devices will mark the beginning of development as full-fledged technologies for the Internet of Things. It should be noted that the simplest smart plug devices based on DECT technology are already on the market. For example, AVM produces the FRITZ! DECT technical product line.
Soon, our team plans to assemble a full-fledged DECT over IP stand and start developing and testing various IoT technologies. Note that we are interested in cooperation with various groups of researchers and are ready to discuss various options for such cooperation.
 ETSI, "DECT-2020 New Radio (NR); Part 1: Overview; Release 1," European Telecommunications Standards Institute, Technical Specification (TS) 103 636-1, July 2020.
 Boyd B. et al., Building Real-time Mobile Solutions with MQTT and IBM MessageSight. – IBM Redbooks, 2014
Andrei Sukhov ([email protected]) is a professor and head of the Network Security Research and Study Group of HSE University, Moscow, Russia. In 2020, he was elected as a senior member of the ACM. Igor Sorokin ([email protected]) is a postgraduate student in the Department of Computer Engineering of HSE University, Moscow, Russia.